In certain industries it is necessary to remove as much of an original environment from contact with a product packaged in a container as possible, and to replace it with a new environment. This is particularly critical in the food industry since many foods are susceptible to attack and spoilage from oxygen, and can be preserved much longer in substantially oxygen-free environments. Various techniques are known for removing or minimizing the oxygen content in packaged materials, including use of vacuum in various manners to reduce the residual oxygen content, use of alternate environments such as inert gases to displace or expel undesired oxygen, and combinations of these techniques. For example, U.S. Pat. No. 4,658,566 discloses a uniquely advantageous apparatus for subjecting a continuous sequence of containers to a controlled environment such as a vacuum, and U.S. Pat. Nos. 5,001,878 and 4,905,454 disclose respectively apparatus and methods for exposing the interior of containers to multiple environments such as vacuum and inert gas.
Although such techniques provide excellent results in most circumstances, there are certain materials which present unique difficulties in oxygen-free packaging. For example, finely powdered materials may trap gases within the packed material such that normal techniques for applying e.g. vacuum and inert gas through a top opening of the container may not expel all of the desired oxygen near the bottom of the container. Various techniques have been suggested for overcoming this problem. For example, U.S. Pat. No. 1,406,380 discloses a process for packaging powdered milk in a sterile atmosphere by means of a plunger which is inserted through an opening in the container and forced through the powder to extend substantially to the bottom of the container. A vacuum is then applied to the upper region of the container through a first channel in the plunger, while carbon dioxide or other suitable gas passes through a second channel in the plunger to exit near the bottom of the container, forcing the majority of air out of the container. In U.S. Pat. No. 3,670,786 a reciprocating needle is lowered into an empty vile to inject inert gas into the vile, expelling oxygen-containing atmosphere from the vile prior to filling with e.g. oxygen-sensitive pharmaceuticals. Finally, U.S. Pat. No. 2,149,790 discloses an alternative process for packaging powdered material such as powdered milk, wherein solid needles or the like are pressed into the material and retracted, leaving open spaces in the packed material which permit vacuum or other alternative atmospheres to access a larger exposed volume of the bulk material, and channels for the original atmosphere to exit.
Unfortunately, the known techniques for packaging materials such as powdered milk have several drawbacks. For example, it is desirable today to provide the consumer with a measuring device or scoop within the package. Such scoops are typically inserted into inverted empty or partially filled containers before the majority of the powdered material is added, so that they will reside near the upper surface of the container when opened by the consumer. As previously noted, it is necessary to remove substantially all of the oxygen from the interior of the container prior to sealing the container. Although the U.S. Pat. No. 1,406,380 discloses a plunger which introduces oxygen-displacing gas near the bottom of the container to facilitate removal of the undesired oxygen, use of such a plunger is incompatible with packaging including scoops. For example, if the plunger encounters the scoop, the scoop could be damaged or could interfere with proper operation of the plunger leading to general failure of the process. Specifically, if the plunger is prevented from reaching the bottom of the container, undesired residual oxygen may remain within a portion of the bulk material, contaminating the product.
Accordingly, one object of the present invention is to provide an apparatus and method which will impart a controlled environment to selected regions of the interior of containers, while accommodating the possible presence of obstructions within the container. In particular, it is an object of the present invention to provide such an apparatus and method which will allow successful removal of substantially all oxygen from e.g. powdered infant formula, in a continuous automated process wherein the formula containers may also contain obstructions such as scoops. A related object is to provide such an apparatus and method which minimizes sources of potential contamination, and is economical to construct and operate. A specific object is to provide such an apparatus and method which is adaptable for use with numerous sizes and configurations of containers, and for packaging numerous materials and providing various forms of alternate environments as desired.
These and other objects shall be apparent in light of the present specification.